Common peripheral input devices of a computer include a mouse, a keyboard device, a trackball device, and the like. The keyboard can be used by users to directly input words and symbols to the computer and is therefore draw attention from users and input device manufacturers. A keyboard including a scissor-type connecting element is pretty common.
Subsequently, the architecture of a key structure in a keyboard having a scissor-type connecting element is described. Referring to FIG. 1, FIG. 1 is a schematic cross-sectional side view of a conventional key structure. A conventional key structure 1 includes a key cap 11, a scissor-type connecting element 12, an elastic rubber body 13, a membrane switch circuit 14, and a baseboard 15, and the baseboard 15 is configured to bear the key cap 11, the scissor-type connecting element 12, the elastic rubber body 13, and the membrane switch circuit 14. The scissor-type connecting element 12 is configured to connect the baseboard 15 and the key cap 11.
The scissor-type connecting element 12 is located between the baseboard 15 and the key cap 11 and separately connects the baseboard 15 and the key cap 11. The scissor-type connecting element 12 includes a first frame 121 and a second frame 122. A first end of the first frame 121 is connected to the key cap 11, and a second end of the first frame 121 is connected to the baseboard 15. The elastic rubber body 13 is surrounded by the scissor-type connecting element 12, and the membrane switch circuit 14 has a plurality of key connecting points (not shown). The key connecting points output corresponding key signals when being triggered. The elastic rubber bodies 13 are disposed on the membrane switch circuit 14 and one elastic rubber body 13 corresponds to one key connecting point. When an elastic rubber body 13 is triggered, the elastic rubber body 13 deforms and presses a corresponding key connecting point in the membrane switch circuit 14, to generate a key signal.
Subsequently, the operation of a conventional key structure 1 when being pressed by a user is described. In FIG. 1, when a user presses the key cap 11, the key cap 11 is under a stress and pushes the scissor-type connecting element 12 to move. Therefore, the key cap 11 may move downwards relative to the baseboard 15 and presses a corresponding elastic rubber body 13. At this time, the elastic rubber body 13 deforms and presses the membrane switch circuit 14, to trigger a key connecting point of the membrane switch circuit 14, so that the membrane switch circuit 14 outputs a corresponding key signal. When the user stops pressing the key cap 11, the key cap 11 is no longer under a stress and stops pressing the elastic rubber body 13, so that the elastic rubber body 13 recovers to the original state due to its elasticity and meanwhile provides an upward elastic restoring force, and the key cap 11 is therefore pushed back to the position before being pressed. The foregoing is the structure and operation of a conventional key structure.
With advances of science and technology, users have an increasingly requirement for light and thin of keyboards, and manufacturers of keyboards are focused in research and development of a thinner and lighter key structure. However, the key structures developed by the manufacturers are still limited by the structure of the connecting element such as the scissor-type connecting element that connects the key cap and the baseboard, and the reduction in thickness is limited. Therefore, a key structure using a flexible key cap is provided on the market. The flexible key cap is made of an elastic rubber material. No scissor-type connecting element is disposed in such the key structure and the thickness of the key structure can therefore be reduced.
However, a new problem appears without configuring a scissor-type connecting element: uneven stress is apt to occur to the flexible key cap. For example, when a user presses a corner of the flexible key cap, a pressing force applied to the flexible key cap by the user cannot be conducted from the corner to the whole flexible key cap because the flexible key cap is made of a flexible elastic rubber material and the support force of the flexible key cap is not sufficient without configuring a scissor-type connecting element. That is, uneven stress of the flexible key cap is apt to occur when the user presses, and therefore it is impossible to generate a key signal, resulting in maloperation.
Therefore, a key structure having a thin and light appearance and capable of avoiding maloperation is needed.